Stoker apparatus



April 25, 1944. D. J. MOSSHART STOKER APPARATUS Filed Nov. '7, 1939 Fla 1.

2 Sheets-Sheet i WITNESSESZ INVENTQR v 001mm J. MossHnRTI ATTORNEY April 25, 1944.

D. J. MossHAR'r STOKER APPARATUS Filed Nov. '7 1939 F I q. 2.

2 Sheets-Sheet 2 35 as Q I m 35 INVENTORV DounmJ. MOSSHRRT- I; W M

ATTORNEY Patented Apr. 25, 1944 STOKER APPARATUS Donald J. Mosshart, Springfield, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 7, 1929, Serial Nb. 303,197

4 Claims.

My invention relates to inclined stokers incorporating a multiple retort underfeed section followed by an overfeed section having moving grate elements for agitating the fuel bed passing thereover and it has for an object to provide a rear water wall which extends upwardly and over the overfeed section in suitable, spaced relation with respect to the latter so as to improve combustion and to avoid stratification of gases passing upwardly in the furnace chamber from the fuel bed.

With stckers of the underfeed type, the over- ,all effective length may be increased by the provision of an overfeed section of suitable length;

and, in order that the fuel bed may be effectively handled by the overfeed section, it is desirable that the latter shall incorporate movable grate elements which agitate the fuel bed to break up fused masses and to secure more thorough permeation of the bed by air. There is a tendency for the gaseous media issuing from the overfeed section to pass upwardly in a stratified condition, that is, adjacent portions of the upwardly moving gases may have a wide variation in the ratio of combustible to air, some portions being overrich in combustible and some having excess air; and, in extreme cases, stratification may result in such incomplete combustion that smoke in substantial quantities is discharged. The irregularity in gaseous media issuing from the overfeed section will be apparent when one considers what occurs when a fused mas is fractured due to agitation. Immediately, there ensues vigorous emission of volatile matter and the local air supply may be inadequate to promote complete combustion immediately above the fuel bed. On the other hand, the reverse situation may occur with respect to an adjacent region on the overfeed section, this being particularly true as the rear end of the overfeed section i approached. Ac-

cordingly, therefore, I provide a water wall form-' is thereby secured. Aside from the wall promoting turbulence to secure more complete combustion of the gaseous media, it also serves to defiect particles of fuel or ash from the gas stream and backwardly onto the fuel bed to reduce the quantity of such particles that may be carried along with the gase through the gas passage of a boiler installation, whereby the amount of such particles deposited on the baflles, the tubes, and possibly carried out through the stack, may be substantially reduced. A further object of my invention is, therefore, to provide combustion apparatus having these advantageous features of construction and operation.

A further object of my invention is to provide an inclined multiple retort stoker having an overfeed section including movable grate elements together with a rear water wall which overlaps the overfeed section and in suitable spaced relation with respect to the latter to promote turbulence of gaseous media issuing from the fuel bed on the overfeed section together with means for admitting secondary air through the water wall at the upper end of the portion which overlaps the overfeed section.

A further object of my invention is to provide for an inclined stoker, including a multiple retort underfeed section, an overfeed section including movable grate elements for agitating the fuel bed passing thereover and a horizontal orifice normally filled with ash and refuse to seal the furnace chamber and through which ash and refuse is continuously discharged due to the push-' ing effect of the moving elements of the overfeed section, a water wall which forms the top wall of the orifice and which extend upwardly and forwardly toward the front wall of the furnace chamber and in suitably spaced relation with respect to the overfeed section so as to cover the latter in order to promote more thorough turbulence and a mixture of the gaseous media issuing from the fuel bed, to minimize stratification and smoke and to promote a longer path of gas travel through the furnace chamber in order to effect more complete combustion.

v These and other objects are effected by my invention as will be apparent from the following description and claim taken in connection with the accompanying drawings, forming. a part of this application, in which:

Fig. l is a-v'ertical sectional view showing my improved water wall construction in relation to the stoker and to the furnace chamber and boiler;

and

Fig. 2 is a view similar to Fig. 1, but showing a continuous ash discharge type of stoker.

Referring now to the drawings more in detail, an inclined stoker, at Ill, forms the bottom wall of the furnace chamber H, the stoker being of tion 'portion26 furtherfai'ds inpromoting turbua well-known type and including a multiple retort underfeed section l2 followed by an overfeed section It, the overfeed section comprising a multiplicity of moving grate elements indicated generally at [4 and which serve to agitate the fuel bed passing over the overfeed section and to promote the travel thereof in the direction of fuel feed.

A water wall l5 including upwardly-extending parallel tubes l 6 extends upwardly at the rear of the discharge end of the overfeed section and I and refuseare'discharged'by means of theclinker grinder iil, the accumulations of ash and refuse in the pit i! above the clinker grinder serving in theusual way to seal the furnace chamber ll against the ingress of air. In this embodiment,

the water wall includes: 7 the lower header 29 from which the first vertical section, at 2|, extends upwardly to a rear wall portion common both to the ash pit I :and'to the furnace chamber jiflg a second section, 1 at 22, continuous with the first section, at 2l, "and whi ch extends u wajrdly and forwardly toward the front wall 23 of the furnace chambe'rso as to cover or overlap the vertical projection of the ash pit H; a third "section, 'at2d, continuous with the-second section and which extends upwardly and forwardly toward the front'wall 23 but with greater degree of horizontal component of directionthan the "second sectionfarid a fourthse'ction, at 25, continuous with the third section and which extend sjupwardlygthe junction of'the sections 24 andr i' fiproviding'an angular or re-entrant porfti dntii, which, with the {furnace fro-ntwall forms {an orifice area in the "furnace chamber "ab ove thestoker.

H dn' air chambert'l is arranged transversely and rearwardly of the junction portion 26 so that spaces betweentubes ;at the junction portion hiay iprovide openings forissuanceof air from .the chamber'z'l 'into'thefu'rn'ace chamber H. 'Air 'isfsupplied to'th'e chamber ZT'by a conduit 28, in turnJsuppliedbyjany suitable means. As shown in Fig. 1, air issupplied'tothe conduit 28 from the'conduit '29 connecting. the air preheater 3E! with'the plenum chamber 3fl of the stoker, the

conduits havingdampersBZ and-33 to secure appropriate divisiorrof theair. v i

Aside from the feature of having the water [wall I overlap th e 'overfeed section to promote turbulence of -gases and more thorough combus- 'tion,,theadmission, of "secondaryair at the junclence and more effective'ahd completecombus- 'ti'on, particularlyfas such air "admitted generally. infa horizontal direc'ztion and transversely of thethr'oat or orificeof the gaseous fiow passage cf thefurn ace and boiler chamber.

I Furthermore, theoverlappiirg water wall feature and the 1 secondaryair admission assists-in ,the settlement fc-f' parceisgearrie's fr'o'rnthe overfeed'section by [the gasfstreamfback onto j theunderfeed section ""andpromctes', for a given" fur'riace' chamber volume, a relatively long path of gas travel, the length being increased because of the sinuous nature given thereto by the overlapping wall feature and by the energy of the entering secondary air. Furthermore, by having the secondary air admitted through the junction portion 26, it is assured that, not only shall the effect thereof be uniform throughout the width of the stoker, but it is admitted to a region having a minimum distance with respect to the horizontal dimensions of the furnace chamber, with the result that most efiective penetration of the gas stream by the transverse stream of entering secondary air is secured.

7 Fig. 2 shows an embodiment of my invention for use'with a continuous ash discharge type of Stoker. With this type, instead of having an ash pit normally having ash maintained therein by the clinker grinder to effect an air seal and from which ash is intermittently discharged by operation of the clinker grinder, such-a pit and clinker grinder are omitted, ash being discharged through a horizontal orifice, at 35, defined by the ash plate '35 and the upper wall 37, the orifice, at

35, being normally filled with ash and refuse to secure the desired-sealing of the furnace chamber against the infiltration 'of air. The orifice is so designed, and the ash plate 36 is so adjusted with respect to the reciprocating movement of the last grate member 54 of the overfee'd section that the pushing effect imparted by such last "grate member serves to fed ash and refuse continuously through the orifice without undue accumulation thereof in front of the orifice. In this embodiment, the water wall lfia a different form, it being comprised by the following sectioris: afirst'horizontal section, at '38, whose end is connected to the header 39 and which'forms the upper wall of the orifice 35; a second upright or vertical section, at '49, continuous with the section, at 38, and which extends upwardly; a

third section, at H, continuous with the second section and which extends upwardly and forwardly toward the front wall 23ao'f the furnace cl'iarriber so a's toov'erlap the overfeed section l3a;

and afourthsectiomat #2, continuous with the third section and which extends upwardly and preferably also rearwardly. The vertical extent "of the second section, at" l0, is determined by the desired spacing of the upwardly and forwardly inclined section, at Al, withrespect to the overfeed-section 13a, this'space being so chosen as -ture of the g ases is'suing -fro'm' the "overfe'ed sectioh, but the directive "effect 'of such wall causes the stream of such gases to' be'proiected forwardly toward the-front 'wall 6f the furnace chamber with' the result that suchgases are caused to n'iix thoroughly with 'gases' issuing 'from t'he -underfeed sectioh, whereby more therougnmixture of all-of the gases and comb'ds'tionmay-be secured. hlso,

' as already pbintedout, "this forward direc-tive 'effectpromotes deposition of ash-and particles ba'clronto theunderfeed section and gives a longer pathof gastravel'a'nd, therefore, an increased -ti-n1e-element-for a given-gas'velocity-to promote more complete combustion.

While I 5 have shown 'my invention in "several forms,'it willbe obvious-to those skilled in -the artthatit is not so limitedfbutdssusceptible of "various other changes-and 'modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. The combination with a stoker forming the bottom of a furnace chamber and including a multiple retort underfeed section followed, in the direction of fuel feed, by an overfeed section including a plurality of pivotally-connected links providing for undulatory movement, agitation, breaking open and crumbling of the fuel bed passing thereover: of a water wall forming the back wall of the furnace chamber and including upwardly-extending water tubes, said water wall including a first section extending upwardly at the rear of the discharge end of the overfeed section and a second section continuous with the first section and which extends upwardly and forwardly toward the furnace chamber front wall and in spaced relation with respect to the overfeed section so as to cover substantially the latter.

2. The combination with a stoker forming the bottom of a furnace chamber and including a multiple retort underfeed section followed, in the direction of fuel feed, by an overfeed section includi'ng a plurality of pivotally-connected links providing for undulatory movement, agitation, breaking open and crumbling of the fuel bed passing thereover: of a water wall forming the back wall of the furnace chamber and including upwardly-extending parallel tubes; said water wall including a first section extending upwardly at the rear of the discharge end of the overfeed section, a second section continuous with the first section and extending upwardly and forwardly toward the front wall of the furnace chamber and in spaced parallel relation with respect to the overfeed section so as to cover substantially the latter, and a third section continuous with the first section and which extends upwardly.

3. The combination with a stoker forming the bottom of a furnace chamber and means including spaced upper and lower walls defining an ash discharge orifice which is normally filled with ash to form an air seal and through which ash is continuously discharged, said stoker comprising a multiple retort underfeed section followed, in the direction of fuel feed, by an overfeed section including moving grate elements for agitating the fuel bed and for imparting a pushing effect to ash passing through the orifice: of a water wall forming the back wall of the furnace chamber and including upwardly-extending parallel water tubes; said water wall including a first horizontal section forming the upper wall of said orifice, a second section continuous with the first section and extending upwardly, a third section continuous with the second section and extending upwardly and forwardly toward the furnace chamber front wall and in spaced substantially parallel relation to the overfeed section so as to overlap substantially the overfeed section, and a fourth section continuous with the third section and which extends upwardly.

4. The combination of a stoker forming the bottom of a furnace chamber and including a multiple retort underfeed section followed, in the direction of fuel feed, by an overfeed section including a plurality of pivotally connected links providing for undulatory movement, agitation, breaking open and crumbling of the fuel bed passing thereover; of a water wall forming the back wall of the furnace chamber, said water wall including a section which extends upwardly and forwardly from the rear of the discharge end of the stoker toward the front of the furnace in spaced relation to and overlying a major portion of the stoker overfeed section, whereby hot gases rising from said overfeed section are directed for wardly to mix with the gases rising from the underfeed section.

DONALD J. MOSSHART. 

